This is a project to study the regulation of carbon pathways in intermediary metabolism of liver and heart tissue at the level of the mitochondrial metabolite transport systems. In particular, the activity of the adenine nucleotide translocase will be correlated with tissue levels of long chain fatty acyl CoA esters and the phosphate potential of the mitochondria and cytosol in the liver during the diabetic state and shortly after the administration of insulin to the animal. Cellular metabolites including adenine and pyridine nucleotides will be measured directly in the mitochondrial and cytosolic compartments following rupture of isolated hepatocytes with digitonin or fractionation of freeze-fixated whole liver tissue in non-aqueous solvents. The ability of insulin to effect the reversible inhibition of the adenine nucleotide translocase by long chain fatty acyl CoA eSters will, in turn, be evaluated as reciprocal changes occur in the metabolic state of the liver during gluconeogenesis and glycolysis, or fatty acid oxidation and lipogenesis. The effect of acyl CoA esters on the distribution of intramitochondrial nucleotides particularly ATP, ADP and CTP will be studied. The results may indicate whether acyl CoA esters can influence oxidative and substrate level phosphorylation at the level of the adenine nucleotide translocase. Mitochondria and contractile protein prepared from normal and ischemic myocardium will be used together with long chain acyl CoA esters to determine whether the poor contractility of the ischemic myocardium is a result of decreased transport of adenine nucleotides across the inner mitochondrial membrane.